首先是在李淼的blog上看到这个东西的，看了一些简介，但是不怎么清楚，后来又在一些数学物理的论文中看到它，这个东西是不是Ｓuperstring里的？

It is referring to the scenario that there are many many possible groud states in the fundamental theory. Many of them are realized in the form of a universe. Our universe is one of them.

This part is a conjecture about fundamental theory. It has nothing to do string theory, which may or may not be the fundamental theory.

One starts to hear landscape being mentioned together with string theory these days since there are some evidences recently that string theory indeed have a lot of vaccuum. Many string theorists, including Li Miao, does not like this possibility since this is somehow against their ideal that they can have a theory which solves everything.

Notice that this is all in principle different from the so called antropic principle, which says that the universe is the way it is because we could not survive otherwise. The existence of a Landscape and other unverses is a precondition for antropic selection to work, but not necessarily leads to it.